Synthesis, thermal and spectroscopic characterization of Caq₂ (calcium 8-hydroxyquinoline) organic phosphor

Bluish-green photoluminescence from calcium 8-hydroxyquinolate (Caq ₂) powder, synthesized by a coprecipitation route, and a blended Caq₂:PMMA thin film is reported. The film was obtained by mixing the Caq₂ powder with PMMA (Polymethylmethacrylate) in a chloroform solution. X-ray diffraction analyses confirm the formation of the Caq ₂ powder and thin film. Further structural elucidation was carried out using Fourier transform infrared spectroscopy (FTIR) in which the stretching frequencies of the Caq₂ bonds were determined. Bluishgreen photoluminescence with a maximum at 480 nm was observed from the powder and the emission was red-shift by 10 nm in the case of the thin film. The UV-vis absorption bands were split and shifted due to different orientations of the Caq₂ molecules in both the powder and thin film. It was confirmed by thermogravimetric (TGA) and differential thermal analysis (DTA) that the Caq₂ powder was stable up to≈380 °C. Atomic force microscopy images showed the continuous distribution of the Caq₂ atoms in the PMMA thin film. X-ray photoelectron spectroscopy data was used to estimate the binding energies of the chemical bonding in the Caq₂ powder complex. The optical properties of the Caq₂ powder and thin film were evaluated for possible applicable in organic light emitting devices.